Gel-carbon nanotube materials: the relationship between nanotube network connectivity and conductivity.
The electrical and mechanical characteristics of composite materials prepared using evaporative casting and vacuum filtration of carbon nanotubes (CNTs) dispersed in the biopolymer s-carrageenan (IC) are reported. It is demonstrated that the contact angle of water with films is proportional to the CNT mass and volume fraction, which is used to compare the properties of buckypapers with those of evaporative cast films. Multiwalled carbon nanotube films were found to exhibit higher conductivity values compared to those observed for single-walled carbon nanotubes composites at comparable contact angle values up to true nanotube volume fraction of 0.12. Buckypapers prepared by varying the absolute amount of CNT mass while keeping the IC amount of mass constant, were found to be more robust and conducting compared to evaporative cast films. In contrast, buckypapers prepared by changing the amount of IC mass while keeping the CNT amount of mass constant were found to be more conducting, but less robust compared to evaporative cast films. It is suggested that the electrical characteristics of these gel-carbon nanotube materials are determined by the relative amounts of mass (or volume) of CNTs and polymer, while the mechanical characteristics are governed by the absolute amounts of mass (or volume).